The invention relates to the field of ground-surface de-icing. More particularly, the invention relates to a device for treating icy ground surfaces. More particularly yet, the invention relates to a device that creates discrete depressions on an ice-covered ground surface.
Keeping ground surfaces, particularly roads and airport runways, free of ice has long been a major problem in geographical regions where temperatures drop below freezing. Over the years, many methods and apparatus have been developed and constructed to clear such ground surfaces of ice. The methods includes scarifying the ice, that is, cutting grooves into the ice to increase the surface area that is exposed to warming rays of the sun. The disadvantage of using an ice scarifier, and indeed, any apparatus using a ground-surface scraping device such as a blade or a rake, is that the downward force that can be applied to the ground surface is limited by the reaction force that can be applied to the vehicle without impairing the ability of the vehicle to travel across the surface.
U.S. Pat. No. 4,842,440 (Alguire; issued 1989) discloses a road grader and scarifier, that is adaptable to serve as an ice-scarifier. According to the Alguire publication, a scraper blade is attached to the bottom of a dump body on a dump truck. During scraping operations, the weight of the dump body rests upon the blade and provides the downward force that is applied by the blade to the ground surface. A disadvantage of this apparatus is that significant downward force must be applied to the ground surface in order to scratch the grooves into it and, thus, it suffers the same disadvantages of scarifiers. A dump truck that is carrying a fully-loaded dump body may provide sufficient downward force for grading a gravel road, but may not provide the force needed to scarify an ice-covered road surface without reducing the traction needed for the vehicle to move forward, or may be able to travel only at a very slow speed.
Numerous other devices and apparatus with rake attachments or cutter blades are known for scarifying or raking ground surfaces. All of these have at least the disadvantage described above with respect to the Alguire road grader, and are generally much lighter in weight and even less suitable for scraping a hard, ice-covered ground surface because of the small amount of downward force that they can apply to the ground surface. It is also known to mount a scraper blade with a serrated edge under the frame of a plow truck, between the front and rear axles, for scraping grooves into an ice-covered ground surface. Again, the plow truck has the same disadvantage as the Alguire road grader.
A particular difficulty in clearing airport runways of ice is that the runway has a specific surface contour that may include grooves. It is important that the runway surface contour not be damaged, and therefore, ice is generally removed chemically. Chemical methods of de-icing ground surfaces include spraying a de-icing fluid or scattering de-icing crystals or solids over the ice-covered surface. One common disadvantage of these two methods is that, as the ice melts, the water flows toward low-lying areas, entraining the de-icing chemicals with it. This effectively removes the deicing chemicals from high-lying areas. For this reason, on critical roadways and runways that require de-icing quickly or have particular surface contours, the ice-covered surface is often first scarified and the de-icing chemicals subsequently applied to the scarified surface in liquid or solid form.
The scarified surface typically comprises a series of contiguous grooves that serve as retaining grooves for the de-icing treatment material. The contiguous grooves, however, are ineffective in retaining the de-icing chemicals because, as the ice begins to melt, the water flows and collects in puddles in low-lying regions of the surface. The result is that on a grooved surface with only a very slight slope or unevenness, the de-icing chemicals will be entrained in the water and flow from the higher-lying regions into the low-lying regions. This effectively removes the de-icing chemicals from higher-lying regions before they have completely melted the ice, thereby leaving potentially large patches of the ground surface scarified, but covered with icexe2x80x94an unacceptable situation for roads and runway surfaces.
What is needed, therefore, is an apparatus that can provide sufficient downward force to make depressions in an ice-covered ground surface without reducing the ability of the prime mover to travel across the surface. What is further needed is a device that will make discrete, random depressions in the ice-covered ground surface such that the surface will serve to retain de-icing chemicals on the surface evenly distributed about the ice-covered ground surface. What is yet further needed is such a device that will not damage the surface contour of the ground surface. And what is still yet further needed is such a device that can be operated at an acceptable speed.
It is an object of the present invention to provide a ground surface treatment apparatus that will create random, discrete depressions on the top surface of an ice-covered ground surface. It is a further object to provide such an apparatus that will provide sufficient downward force to impinge on the ice-covered ground surface without losing its ability to travel across the ground surface at an acceptable speed. It is a yet further object to provide such an apparatus that will follow the contour of the ground surface and not damage the contour.
The objects are achieved by providing an ice-scruffing device that creates a scruffed or textured surface on an ice-covered ground surface. The term xe2x80x9cscruffedxe2x80x9d shall be used herein to refer to a surface having random depressions or indentations, such as pock-marks, pitting, and/or cracks, as opposed to grooves, slits and/or punctures. The term xe2x80x9cscruffedxe2x80x9d also includes shattering of the surface, such as when hard, blue ice surface is impacted with a small hard object. Analogously, the device of the present invention is referred to as an xe2x80x9cice scrufferxe2x80x9d and is a device that creates a scruffed surface on an ice-covered surface such as an iced roadway or runway, or a roadway packed with hard snow or covered with heavy slush.
The ice scruffer of the present invention is a drum fitted with a plurality of paddles, each paddle fitted with a series of strike elements, also called xe2x80x9cabradersxe2x80x9d or xe2x80x9cscruffing elements.xe2x80x9d The drum is mounted in a frame and extends transverse to the travel direction of the frame, which is pulled or pushed along the ground surface by a prime mover. The drum and the frame are similar to the drum and frame disclosed by the inventor of the present invention in U.S. Pat. No. 6,260,293 (issued 2001), which is herein incorporated by reference. The paddles of the ground-cleaning apparatus of the just-mentioned patent are replaced by the paddles of the ice scruffer according to the present invention to provide a device that does not clean, i.e., pick up material or debris from the ground surface, but rather, scruffs the upper surface of the ice-covered or snow-packed ground surface to create a surface that has randomly placed, discrete depressions. Furthermore, since the apparatus of the present invention does clean the ground surface, it also does not require the impeller/discharge assembly of the ground-cleaning apparatus.
The ice scruffer paddle includes a series of stiffly flexible cables that are fastened to the paddle at one end, each cable ending in a small, hard strike element also referred to as an impactor. As the drum rotates, the paddles rotate radially about the rotational axis of the drum, thereby swinging the strike elements attached to the ends of the cables with a greater velocity than that of the core of the drum. The ice scruffer is adjustable in height, and ideally, the apparatus is adjusted so that the impactors strike the ground surface and penetrate the surface to a depth that provides an indentation of the desired depth. The ice scruffer is pivotably mounted in a frame so that it can pivot or swing slightly about a roll axis and/or a pitch axis and, therefore, can follow closely the contour of the road or runway without damaging the contour.